Membrane roofing refers to a number of different roofing materials. Historically, the most common type was a tar and pitch membrane, but newer synthetic materials are quickly taking over. For a flat roof, these newer synthetic membranes offer a great leak proof option.
Membrane Roofing for Flat Roofs
Traditionally, the best way for home builders to get water off the roof has been to add a simple slope to the roof. Four centuries, sloping a roof has been almost the only way to ensure that rain and precipitation doesn’t pool on the roof. More recently builders have been designing buildings with flat roofs, which presents unique challenges for drainage.
A flat roof does not have the advantage of gravity for draining rain, snow, and other precipitation. In fact, on a flat roof, gravity is your enemy. Water is very good at finding a way, and gravity will always gather water to the lowest spot. If a roof has any sagging or is otherwise not completely even, water will pool. Pooled water is very prone to leaking. Any seams, cracks, or holes in the roofing provide a path for the water to follow gravity. After all, water always flows to the lowest spot.
When building a flat roof, it is incredibly important to find a way to get the water off the roof without letting it pool and leak into the structure below. This can be done by introducing a very gentle, almost imperceptible slope to the roof, to direct water towards a gutter or drain. But even with this slight slope, it is important that the roof be completely watertight.
Traditionally, flat roofs were covered with asphalt, a mixture of pitch, tar, and gravel. To make a flat asphalt roof a roofer lays down roofing felt and then spread hot tar over it. The roofer applies the tar, pitch, and gravel mixture in many layers. With enough layers, the roofer can create a watertight seal.
It takes a good deal of skill to install a proper watertight roof with this method. Although this was the main form of roofing for flat roofed structures until 25 or 30 years ago, it is becoming more and more rare. It is a labor intensive process that requires the roofer to mop on the tar and pitch mixture, a smelly, hot, and messy process. If it is not done correctly, leaks are almost guaranteed.
Synthetic Membranes for Flat Roofs
Due to the challenges of asphalt for flat roofs, new synthetic roofing membranes have been increasing in popularity. Synthetic roofing membranes fist came on the scene in the 1950s. They increased in quality and became more common as materials science advanced. With new developments in rubber and plastic materials, it was possible to create very secure and watertight roofing membranes.
These modern membrane materials are much easier to install and produce a more secure seal. With a more secure seal these membranes can create roofs that are almost completely leak proof. In the past, a flat roof was almost sure to leak eventually, but with modern synthetic membranes leaks may be very rare or may never happen at all. This has been a great advantage for owners of homes, businesses, and other structures designed with flat roofs.
There are a number of different synthetic membranes available today. Generally, they fall into three categories.
The advantage of thermoset membranes is in how the strips of roofing material attach to each other. Traditional roofing materials had to have some kind of joint. Metal roofing materials could be soldered together. Asphalt roofs didn’t come in pieces at all and had a completely different application method. But with thermoset membranes, a whole new joining method could be achieved.
With thermoset membranes, the strips of roofing material literally become a single piece, all the way down to the molecular level. Many of these roofs fall into the synthetic rubber category. Some common names are EPDM, CSPE, CR, and ECR membranes. The important thing to know is that for all of these types of roofing, the individual strips of material, once joined, are chemically cross-linked.
Chemical crosslinking means that once the seams have sufficiently cured, the actual molecules of the individual roofing strips are joined, creating a single giant sheet of roofing over the entire structure. When done properly–that is, according to manufacturer’s specifications–it is possible to install a roof that will be leak proof for many, many years. You are basically shrink-wrapping the roof in a single piece of rubber.
Thermoplastic membranes are, as the name implies, basically plastic. There are a number of acronyms used for different types of thermoplastic roofing membranes. The most familiar is PVC, polyvinyl chloride. This is the same materials in PVC pipes and other home building items. Other, less familiar acronyms include CPA, CPE, EIP, NBP, PIB, and TPO. These are all basically types of plastics.
The main difference between thermoplastic roofing membranes and thermoset membranes is how the individual pieces of roofing are joined. Unlike thermoset roofing, thermoplastic roofing does not chemically crosslink. Instead, seams are connected with solvents or heat that weld the two pieces together. This does not technically result in a molecularly consistent material over the whole roof. But if done properly, these seams can be just as strong as the materials themselves.
A thermoplastic roofing membrane should be watertight and leakproof for many, many years. Unlike a traditional asphalt roof, there is almost no entry point for water to infiltrate the roof and get down into the structure below.
Modified bitumen is basically an evolution of asphalt roofing. In a modified bitumen roof, the tar, pitch, and gravel that make up the asphalt is mixed with solvents, rubber modifiers, or other synthetic ingredients.
There area number of different ways to install a modified bitumen roof. It can be applied in strips that are joined with heat. It can also be hot mopped on just like the older asphalt roofs. Recently, new materials can be joined without heat.These materials use special adhesives that don’t require heat or they are self-adhesive.
While a modified bitumen roof is not as advanced as a fully synthetic roof, it is still a better option that the old asphalt roofs. It creates a better, stronger, more leakproof seal that degrades more slowly than classic asphalt.
Installing a Membrane Roof
Any roof installation should begin by contacting Eagle Watch Roofing. When you contact our representatives, we will provide a no cost and not obligation roof inspection. The inspection will help us to determine the unique needs of your project. We can do both residential and commercial roofs.
Once we have an idea of what your project entails, we can get you a written estimate. The estimate includes all labor, materials, and accessories, so you will know exactly what is going into the quoted price. Once we have agreed on a price, Eagle Watch Roofing will oversee the whole project from start to finish. You don’t have to worry about anything until the project is complete and we walk you through your new roof.
When we do the walk through we will answer any questions and address any concerns. When you are totally satisfied we will ask for payment and provide a written warranty, although we doubt you will have to ever use it.